Ventilation fan is commonly used ventilation equipment. A known ventilation fan generally comprises: a frame provided with an opening in a bottom surface thereof and a flange, the frame having a rectangular shape; a casing with a fan motor installed therein; and an adapter connected to an outlet of the casing. And a ventilation fan installed between a roof and a ceiling is usually mounted through a bracket or a hanger, or through providing a bore in the flange of the frame and threading a screw to pass through the bore in the flange and a gap and into a specific joist which has the same width with the frame, so that the frame is mounted to the joist.
The components (such as, frame, casing, adapter, and the like) of the above known ventilation fan can be packed separately, and a user should assembly the components together after purchase. When packaging several frames integrally, since a volume of a frame is large, there is a need for more packing materials, which leads to a relative high cost for the packaging.
Moreover, when mounting the conventional ventilation fan to the joist, there needs a bracket or a hanger, such that not only the cost for mounting is increased, but also additional installation steps and hours are needed.
In the method of threading a screw to pass through the bore in the flange and a gap and into a specific joist having the same width with the frame so as to mount the frame to the joist, the gap between joists should be the same as the width of the frame, which limits of the usage of the method.